The objective of the program is to gain increased understanding of neural mechanisms which underlie hearing through an integrated series of studies: 1) determination of the mechanical vibration patterns of basilar membrane using both the Mossbauer technique and laser interferometry; 2) anatomical and electrical recording studies on the organ of Corti of the mouse in tisue-culture; 3) recordings from single auditory-nerve fibers responding to complex acoustic stimuli, including vowel approximations, and to electrical stimuli delivered with micropipettes or with an implanted cochlear prosthesis; mathematical modeling of peripheral auditory system; 4) recordings from single neurons in the cochlear nuclear complex in cat to assess both cochlear output and the transformations imposed by neurons in the complex on information received from auditory-nerve fibers; 5) combined anatomical and electrophysiological studies on the functional organization of auditory cortex. Multidisciplinary methods are used, including microelectrode stimulating and recording techniques with special emphasis on the study of the coding of auditory stimulus information in the temporal discharge patterns of single neurons. Computers are used extensively in controlling the parameters of auditory stimuli, in the collection and analysis of anatomical and physiological data, and in mathematical modeling. Histological identification of recording sites and cytoarchitectonic studies are performed; anatomical techniques include tract-tracing techniques, quantitative single-cell measurements, and electron microscopy.